Since the discovery of the Higgs boson, physicists have searched and searched for any hint of new particles. That search has been fruitless. Until, perhaps, now. Today on Space Time Journal Club we’ll look at a paper that reports a compelling hint of a new particle outside the standard model: the sterile neutrino.

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Regular neutrinos are a bit aloof. They don’t interact by the electromagnetic or strong nuclear forces – only by the weak nuclear force and gravity. They are so weakly interacting that they pass through matter like it isn’t there. To have a 50-50 chance of stopping any given neutrino you’d need a wall of lead … one light year thick! If regular neutrinos are aloof, then sterile neutrinos are the complete loners. They don’t even interact via the weak interaction. Even so, detection of sterile neutrinos would be incredibly important. Besides being the first expansion of the standard model family since the Higgs boson, sterile neutrinos are a candidate for dark matter, and their existence would have had a huge influence on the expansion of the early universe.